Process for preventing corrosion



United States Patent PROCESS ron PREVENTING coRnosIoN Jerome Green, Chicago, Ill., assignor to National Alummate Corporation, Chicago, 111., a corporation of Delaware No Drawing. Application April 20, 1954 Serial No. 424,507

Claims. (Cl. 252-855) This invention relates to the inhibition of corrosion of corrodible ferrous metal surfaces by corrosive fluids and more particularly to a'process for inhibiting the corrosivity of fluids produced from sub-surface earth formations which are brought into contact with corrodible ferrous metal tubing and other equipment through which the fluids flow and in which they are processed.

It is well known that in the, production of oil and gas soluble sulfides carbon dioxide, and other substances are often produced from subterranean formations and in the presence of water will attack or corrode ferrous metal pipes and other equipment with which the crude oil or gas comes into contact. Furthermore, along with oil or gas, there is usually produced brine which is very corrosive. In wells producingso-called sour crude or sour gas, the corrosion problem is particularly acute.

Unless precautions are taken to reduce or prevent corrosion, the tubing, rods, valves and other metal parts of the equipment may require replacement at frequent intervals. Such replacements can be and often are extremely expensive. The expense is not limited merely to the cost of replacing the corroded equipment but may also involve shutting down the well in order to make repairs and replace the equipment. Sometimes corrosion is so severe as to result in failure of the equipment in which case the well may run wild and enormous losses may be incurred.

To give a specific illustration of the corrosion problem,

I in a particular group of wells producing on the average of 25% oil and 75% water at the rate of 50 to 200 barrels of oil per well per day steel sucker rods failed in about two months. Ordinary steel ball-and-seat valves failed in one to two weeks. Metering equipment failed in a very short period of time.

One of the objects of the present invention is to provide a new and improved method of inhibiting corrosion of corrodible ferrous metal surfaces by corrosive fluids.

A further object'of the invention is to provide a new and improved method of inhibiting corrosion of corrodible ferrous metal surfaces by a chemical treatment which is simple and economical.

Another object of the invention is to provide a new and improved method 'of inhibiting corrosion in oil and gas wells by a down-the-hole treatment.

A more specific object of the invention is to provide a new and improved down-the-hole treatment for inhibiting corrosion of ferrous metal surfaces in equipment which comes into contact with fluids produced in oil and .gas wells normally producing sour crude oils or sour gas.

Another object of the invention is to provide a method 'of-inhibiting corrosion in ferrous metal equipment of oil and gas wells by a down-the-hole treatment which does not form precipitates with components of the fluids in the wells that would tend to plug the formation or otherwise interfere with the flow of oil or gas. Other objects will appear hereinafter.

In accordance with the invention the corrosion of ferrous metals exposed to corrosive fluids is inhibited by applying to the ferrous metals, preferably by dissolving in the corrosive fluids, an effective amount of a quaternary imidazoliuium salt, preferably a quaternary imidazolinium nitrite, having in the 2-position a higher aliphatic group containing 8 to 36 carbon atoms and attached to a quaternary nitrogen atom an aralkyl group and preferably also a lower aliphatic hydroxy hydrocarbon group. I

The quantity of the aforementioned quaternary imidazolinium salt required for the purpose of the invention v is a fraction of a percent by weight of the corrosive fluids to which the ferrous metal is exposed, preferably 1 to parts of the quaternary imidazolinium salt per million parts of total fluids.

Some of said quaternary imidazolinium salts, such as the nitrites, phosphates and bicarbonates, and in general the quaternary imidazolinium salts of weak acids can be employed in concentrations greater than 100 parts per million but such larger concentrations are not necessary in most applications of the invention. Other quaternary imidazolinium salts of the type described, particularly the quaternary imidazolinium halides, including, for example, the quaternary imidazolinium chlorides, are actually very corrosive to ferrous metals when employed in relatively high concentrations in aqueous solutions. In fact, for this reason, concentrated aqueous solutions of these compositions are ordinarily shipped in glass containers. It was surprising, therefore, to discover that relatively minute amounts of these quaternary imidazolinium halides within the range of l to 100 parts per million are effective as corrosion inhibitors.

The compositions employed for the practice of the invention should also preferably be soluble in the corrosive medium to which the metal equipment is exposed. The preferred compounds employed in the practice of the invention are Water soluble and are also soluble in aqueous solutions containing organic solvents, such as alcohols (e.g., methyl alcohol, ethyl alcohol and isopropanol), glycols (e.g., ethylene glycol, diethylene glycol), ketones (e.g., acetone), and dioxane. In practice, it is preferable to dissolve 5% to 25 by weight of the quaternary imidazolinium salt in water containing a sufficient amount of an alcohol e.g., isopropanol, to prevent freezing and to increase the stability of the corrosion inhibitor. The resultant solution is then injected into the corrosive medium by the use of a proportioning pump, or other suitable device, in proper amounts to inhibit corrosion of the metal equipment which comes in contact with the corrosive medium.

The invention is especially advantageous in preventing corrosion of oil and gas well equipment by injecting the corrosion inhibiting composition into the annulus ofthe well between the casing and the producing string where it becomes intimately admixed with the well fluid and may be pumped or flowed from the Well with the corrosive fluids. In this Way, the inner wall of the casing and the outer and inner walls of the tubing string and the inner surface of the auxiliary equipment, including well head equipment, flow lines, and the like, are contacted with the quaternary imidazolinium salt and protected from corrosion caused by corrosive materials in the well fluid.

The corrosion inhibiting compositions employed in the practice of the invention are also useful in other applica- 2,sss,4oo

tions, for example, in preventing or reducing corrosion in cooling tower equipment. In many such applications, slimes and other growths produced by bacteria or algae or other micro-organisms are also a problem and make it necessary to clean the apparatus frequently. The compositions of the present invention have the advantage that they not only inhibit corrosion but are also effective in destroying micro-organisms that produce growths of the in which R, R R R and R are organic groups of the same or different kinds as hereinafter described and X is an anion. The radicals R and R are each linked through a carbon atom to the quaternary nitrogen atom N. The radical R is a higher aliphatic group containing 8 to 36 carbon atoms in an acyclic carbon chain (e.g., octyl, nonyl, decyl, undecyl, dodecyl, undecenyl, tridecyl, tetradecyl, pentadecy'l, hexadecyl, heptadecenyl, oleyl, octadecyl, erucyl, melissyl, hydroxy dodecyl, hydroxy stearyl, ricinoleyl and polymeric radicals derived by the polymerization of materials containing olefinic double bonds). One or both of the radicals R and R is an aralkyl group in which the aliphatic portion of the radical is an acyclic hydrocarbon group (e.g., benzyl, cinnamyl, and homologues thereof). In the event only one of said radicals R and R is an aralkyl group, the other of said radicals is a lower aliphatic radical having not more than 6 carbon atoms and containing a hydroxy group (e.g., hydroxy ethyl, hydroxy propyl, hydroxy butyl, and homologues thereof). The radicals R and R are preferably hydrogen but can be lower alkyl radicals containing not more than 6 carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, isoamyl, and hexyl). The anion X is preferably nitrite but can also be chloride, bromide, iodide, fluoride, sulfate, nitrate, bicarbonate, dihydrogen phosphate, :bisulfite, salicylate, phenate, formate, acetate, propionate and amino acetate. The anion should preferably be one which forms soluble salts with cations encountered under the conditions of use and the quaternary imidazolinium salt should preferably be soluble in the corrosive medium in the concentrations used. The invention will be further illustrated but is not limited by the following examples in which the quantities are stated in parts by weight unless otherwise indicated.

Example I The following is an illustration of an application of the invention in a down-the-hole treatment of oil wells. In this field there were 4 wells and the production consisted of about 25% oil and 75% water at the rate of 50 to 200 barrels total fluid per well per day.

Prior to the introduction of the treatment to inhibit corrosion, one of the problems was failure of the sucker rods. Both steel and alloy sucker rods would fail in about two months. Ordinary steel ball-and-seat valves failed in two weeks. Hydrogen sulfide gas was present in this production. Brines from two of the wells were 4 sampled and when analyzed showed the following compositions:

No. 1 N0. 2

S. p.p.u1 650 Total hardness, p.p.m. as 09.00; .a 15, 500 15, 200 Calcium, p.p.m. as OaCO; 10, 000 ,900 Magnesium, ppm. as GaCO; 5, 50 7, 300 Phonolphthalein alkalinity, p.p.m. as 09.60 520 0 Methyl orange alkalinity, p.p.m. as OaCO 830 1, 040 Chloride, p.p.m. as NaCl 95, 500 95, 000 Sulfate, ppm. as Na so 3, 270 Silica, p.p.n1. as SiOg.-.. 8 Iron, ppm. as Fe 2. 3 Free 00:, ppm. as 0e00, 380

Three wells were treated in accordance with the invention with a composition consisting of the following ingredients:

Percent l-(Z-hydroxyethyD-l-benzyl-2-tridecyl imidazolinium nitrite 10 Water 7O Isopropyl alcohol 20 The above described composition was added to each of these wells at the rate of /2 gallon per day for the first week of the test. The treatment for the remainder of the test was at the rate of 50 ppm. on the basis of total fluids produced. The test period was three months.

On two of the wells there was no maintenance work required during the three-months test period. On the third well only one old ball-and-seat valve failed during this time.

The compound l-(2-hydroxyethyl)-1-benzyl2-tridecyl imidazolinium nitrite can be prepared by passing a 10% by weight solution in water of tridecyl benzyl hydroxyethyl imidazolinium chloride through a column of an anion exchange resin, such as a styrenedivinylbenzene resin containing quaternary amine ion exchange groups (e.g., Nalcite SBR), which has previously been regenerated with a 4% aqueous solution of sodium nitrite. The solution of tridecyl benzyl hydroxyethyl imidazolinium chloride is passed through the column of anion exchange resin at a flow rate of 3 gallons per minute per square foot as described in my copending application, Serial No. 367,767, filed July 13, 1953.

Example II A number of compositions were tested for corrosion inhibition properties by a method adapted to show their ability to minimize the corrosion of subsurface oil well piping and equipment caused by the fluids present in the well.

A vigorously agitated hydrocarbon-brine mixture was prepared by mixing together 50% by volume of No. 2 diesel fuel oil, and 50% by volume of a 3% solution of sodium chloride in distilled water in a 400 ml. beaker. A cover was fitted on the beaker and agitation of the solution begun at 1725 r.p.m. The solution was then deaerated for one hour with carbon dioxide at a flow rate of 3817 ml. per minute. Hydrogen sulfide was then introduced into the gas flow in such a manner that although the total flow rate of gas into the beaker remained at 38:7 ml. per minute the gas actually entering the beaker consisted of equal volumes of hydrogen sulfide and carbon dioxide. This gas mixture was allowed to saturate the solution for the remainder of the test.

After the hydrogen sulfide-carbon dioxide mixture had been bubbled into the solution for one hour, the inhibitor under investigation was added. The amount of inhibitor added was calculated as parts per million (ppm) of the oil phase. A mild steel specimen measuring about 1" x 2" x was then mounted on a hard rubber holder and inserted into the fluids. The test was then allowed to proceed for 18 hours with constant agitation and gas flow.

H At-the conclusion of the test period, the 'gas flow and agitation were halted. I i,. I

The corrosion product was removed from the specimen by means of a soft brush and the specimenwas taken from the holder, cleaned by immersing for 30 seconds in. hydrochloric acid which had been inhibited with formaldehyde (180 ml. of a 40% formalin solution per gallon of 37% acid). The remainder of the clean ingproc :edl.lre consisted of dipping the specimen in a saturatedsoda ash solution, rinsing it in water, dipping in acetone. and air drying. The specimen was then weighed to the closest 0.1 milligram. l The temperature during these tests was approximately 20C.to25C. The effectiveness of the inhibitor was evaluated by calculating the corrosion in terms of milligrams per. specimen per 18 hours. The following results were observed withvarious corrosion inhibiting compositions: Y

Corrosion Quantity,

Rate, mgJlS hrs.

Inhibitor p.p.m.

A. Blank" B. Composition otExample I 0 C. 1- (2 hydroxyethyl) 1 benzyl-Z-trideeyl im dazolininm chloride...

Example III added to the hydrocarbon-brine mixture at a dosage of 250 p.p.m. the corrosion rate was 37.4 mg./18 hrs.

' 7 Example IV The procedure. was the same as that described in Example II except that the corrosion inhibiting composition was a solution of 1-(2-hydroxyethyl)-l-benzyl-2- tridecyl imidazolinium sebacate dissolved in water in a concentration of 7.5 grams per 100 ml. of solution. When this composition was added to the hydrocarbonbrine mixture at the dosage of 250 p.p.m. the corrosion rate was 5.1 mg./ 18 hrs. At a dosage of 100 p.p.m. the corrosion rate was 13.8 mg./ 18 hrs. At a dosage of p.p.m. the corrosion rate was 58.7 mg./ 18 hrs.

Example V hrs. At a dosage of 50 p.p.m. the corrosion rate was 88-.7 mg./l8 hrs Example VI The procedure was the same as that described in Example II except that the corrosion inhibiting composition was a solution of 1-(2-hydroxyethyl)-1 benzyl-2- tridecyl imidazolinium metaphosphate dissolved in water in a concentration of 7.4 grams per 100 ml. of solution. When this composition was added to the hydrocarbonbx ine mixture at a dosage of 250 p.p.m. the corrosion the corrosionrate was 53 .2 mg./.18 hrs.

Example VII The procedure was the same as that. described in Example II except that the corrosion inhibiting composition was a solution of 1-(2-hydroxyethyl)-1-benzyl-2- tridecyl imidazolinium pyrophosphate dissolved in water ina concentration of 7.2 grams per of solution. When this composition was added to thehydrocarbonbrine mixture at a dosage of 250 p.p.m. the corrosion rate was 9.2 m'g./l8 hrs. 'When the same composition was added to, the hydrocarbon-brine mixture at a dosage of 100 p.p.m. the corrosion rate was '5.2mg./18 hrs. At a dosage of 50 p.p.m. the corrosion rate ,was 21.8 mg./18 hrs. j

In a similar manner other compositions can be employed in accordance with the invention to inhibit corrosion. The inhibitor can be added in pure form as in Example II(C) or item be added in solution as in .the other examples. The effective dos'age will vary'to some extent depending upon the corrosive medium. For finstance, the composition of Example" I is not elfective in inhibiting corrosion in'a'mixture of equal parts of gasoline and distilled water in equilibrium with air, under static conditons, at a dosage of 250 parts per million parts of gasoline but is,very efiective at a dosage ,of 1000 p.p.m. At this dosage since the active ingredient constitutes 10% by weight of the corrosion inhibiting composition the effective concentration of the active ingredient is 100 p.p.m. I 7

Examples of other specific compounds that 'can be employed in the practice of the invention are the following:

rate was 48.3 -mg./ 18 hrs. At a dosage of 100 p.p.m.

1 (2 -hydroxyethyl) 1 benzyl 2 tridecyl imidazolinium nitrate 4 p 1 (2 hydroxyethyl) 1 benzyl 2 tridecyl imidazolinium bromide 1 (2 hydroxyethyl) 1. benzyl 2 tridecyl imidazolinium chloride 1 a (2 hydroxyethyl) 1 1 benzyl 2 tridecyl imidazolinium iodide 1 (2 hydroxyethyl) 1 benzyl 2 tridecyl imidazolinium hydrogen carbonate 1 (2 hydroxyethyl) 1 benzyl 2 tridecyl imidazolinium salicylate i 1 (2 hydroxyethyl) 1 benzyl 2 tridecyl imidazolinium benzoate v 1 (2 hydroxyethyl) 1 benzyl 2 tridecyl imidazolinium cinnamate v 1 (2 hydroxyethyl) '1 benzyl 2 tridecyl imidazolinium .propionate v 1 (2 hydroxybutyl) 1 benzyl 2 tridecyl imidazjolinium nitrite. g

1 (2 hydroxybutyl) 1 'benzyl 2 -.tridecyl imidazolinium bromide n I 1 (2 hydroxybutyl) 5 1 benzyl 2 tridecyl imidazolinium chloride 1 (2 hydroxybutyl) 1 benzyl 2 tridecyl imidazolinium iodide 1 (2 hydroxybutyl) 1 benzyl 2 tridecyl imidazolinium hydrogen carbonate 7 V 1 (2 hydroxybutyl) 1 benzyl 2 tridecyl imidazolinium salicylate 1 (2 hydroxybutyl) 1 benzyl 2 tridecyl imidazolinium benzoate 1 (2 hydroxybutyl) 1 benzyl 2 tridecyl imidazolinium cinnamate imidaz- 1,1-dibenzyl-2-tridecyl imidazolinium hydrogen carbonate I 1 2 hydroxybutyl) 1. benzyl :2 heptadeeenyl I' I idazolinium salicylate i I LI-dibenzybZ-ttidecyl imidazolinium salicylate l,1-dibenzyl-2tridecyl imidazoliniurnbenzoate LI-dibenzyl-Z-tridecylimidazolinium cinnamate I I 1 J- dibenZyI-Z-ftridecylIim'idazoliniumpropionate I I I I 1- (2 hydroxyethyl) -1-benzy1--I 2 -Iheptadecenyl idazolinium nitrite idazolinium chloride [idazolinium iodide idazolinium hydrogen carbonate 1 I I 1 1 (2 hydroxybutyl) l benzyl 2 -'I heptadecenyl im I I idazolinium benzoate I I I I 11 (2 hydroxybutyl) --1- benzyl -2 heptadecenyl inn idazoliniumIcinnafrnate Z I I I 1 (2 hydroxybutyl) {1- benzyl 2 heptadecenyl im f idazolinium prop ionate The compositions of the invention are especially useful in inhibiting corrosion of oil and gas well equipment including tubing, meters, pumps, valves and the like. Espe cially advantageous results have been obtained in inhibiting corrosion in oil wells producing sour crude oils but the invention is equally applicable to sweet crude production and also to gas condensation production. While the invention is particularly important in inhibiting the corrosion of corrodible ferrous metal surfaces that are brought into contact with hydrocarbons containing water, it is also valuable in preventing the corrosion of ferrous metal surfaces in contact with other corrosive media containing water.

This application is a continuation-in-part of my co pending application Serial No. 367,767 filed July 13, 1953, now abandoned.

The invention is hereby claimed as follows:

1. A process for inhibiting corrosion of a corrodible ferrous metal in contact with a corrosive fluid from oil and gas wells which comprises applying to said ferrous metal in solution in said fluid a corrosion inhibiting amount of a quaternary imidazolinium salt having in the 2-position a higher aliphatic group containing 8 to 36 carbon atoms and attached to a quaternary nitrogen atom an aralkyl radical and a radical from the group consisting of aralkyl radicals and lower aliphatic hydroxy hydrocarbon radicals.

2.A process for inhibiting corrosion of a corrodible ferrous metal in contact with a corrosive fluid from oil and gas wells which comprises appling to said ferrous metal in solution in said fluid a corrosion inhibiting amount of a quaternary imidazolinium nitrite having in the 2-position a higher aliphatic group containing 8 to 36 carbon atoms and attached to a quaternary nitrogen atom an aralkyl radical and a radical from the group consistim I I I ing of aralkylradicals and lower aliphatic hydrony hw drocarbon radicals. I

olinium nitrite.

4.A process for inhibitingcorrosion of acorrodible I I I ferrous metal in contact witha corrosive fluid from oil I I I I I and gas wells which comprises applying tosaid ferrous metal in solution in said fluid a corrosion inhibiting amount of1-(2-hydroxyethy1)-I-benzy1 2 tridecylIirnidaz-I I I I I :olinium chloride.

inn.

im-I I ,1

I l 2 hydroxyethyl) '1 -Ibenzyl 2 --heptadecenyl IimI-I I idazolinium bromide j 1 (2 hydroxyethyl) 1 benzyl 2 I- heptadecenyl idazoliniu'm chloride I I I I 1 (2 hydroXyethyl) 1 benzyl- 2 -Ihepta ilecenyl im-' idazolinium iodide I I I I 1 (2 -hydroxyethyl) 1 benzyl" 2 --heptadecenyl imidazolinium hydrogen carbonate I 1 (2 -'hydroxyethyl) 1 --benzyl 2 heptadecenyl im- I idazolinium salicylate I j I 1 (2 hydroxyethyl) 1 benzyl 2 heptadec'enyl I idazolinium benzoate I I I I I I I I I l -(2-- hydroxyethyly '1 "--benzyl 2 --heptadecenyl idazoliniumcinnamate I 1' (2 hydroxyethyl) 1 benzyl 2 heptadecenyl im' idazolinium propionate I I I 1 1 (2- hydroxybutyl) 1 benzyl 2 heptadecenyl idazolinium nitrite '1 --(2 hydroxybutyl) -1-- benzyl 2 heptadecenyl imidazolinium bromide I I I II I I 1 (2- hydroxybutyl) 1 benzyl 2 heptadecenyl -5. A process for inhibitingcorrosion of a'corrodible ferrous metal in contact witha corrosivefluid from oil and gas wells which comprises applyingto said ferrous metal in solution in said fluid: a corrosion; "inhibiting I I amount of a quaternary imidazolinium salt havingItheI I generalformulaa I in which is an aliphatic hydrocarbon group containing I 8 to 36 carbon atoms, R1IisIan aralkylradicalin whichanI I I acyclic carbon atom isattached to the quaternarynitro- I gen atom, -R Iis an aliphatic hydroxy hydrocarbon radical containing notmore than 6 carbonatoms' and R andR f I i are from the group consisting of hydrogen and lower alkyl, andIX is an anion. I I

I 6. A process for inhibiting corrosion in oil and gas I. I well equipment which comprises injecting intothe well I 1 a corrosion inhibiting amount of a quaternary imidaz olinium salt having. in the 2-position a higheraliphatic I group containing 8 to 36 carbon atoms and attached to I in which R is an aliphatic hydrocarbon group containing 8 to 36 carbon atoms, one of the radicals R and R is a benzyl group and the other is a hydroxy alkyl group containing not more than 6 carbon atoms, and X is an anion forming a water soluble salt with calcium, barium, strontiurn and magnesium in the concentrations employed.

8. A process for inhibiting corrosion in oil and gas well equipment which comprises injecting into the well a corrosion inhibiting amount of 1-(2-hydroxyethyl)-1- benzyl-Z-tridecyl imidazolinium nitrite.

9. A process for inhibiting corrosion in oil and gas well equipment which comprises injecting into the Well a corrosion inhibiting amount of l-(2-hydroxyethyl)-lbenzyl-Z-tridecyl imidazolinium chloride.

10. A process for inhibiting corrosion of a corrodible ferrous metal in contact with a corrosive fluid from oil and gas wells which comprises applying to said ferrous 626,473 References Cited in the file of this patent 5 52 ,474

UNITED STATES PATENTS Blair Apr. 16, 1949 Lytle Nov. 17, 1953 Rydell Mar. 13, 1956 FOREIGN PATENTS Great Britain July 15, 1949 Great Britain July 15, 1949 OTHER REFERENCES Arquads Solve Costly Water Flood Problems, advertisement in World Oil, April 1954, page 245. 

1. A PROCESS FOR INHIBITING CORROSION OF A CORRODIBLE FERROUS METAL IN CONTACT WITH A CORROSIVE FLUID FROM OIL AND GASS WELLS WHICH COMPRISES APPLYING TO SAID FERROUS METAL IN SOLUTION IN SAID FLUID A CORROSION INHIBITING AMOUNT OF A QUATERNARY IMIDAZOLINIUM SALT HAVING IN THE 2-POSITON A HIGHER ALIPHATIC GROUP CONTAINING 8 TO 36 CARBON ATOMS AND ATTACHED TO A QUATERNARY NITROGEN ATOM AN ARLKYL RADICAL AND A RADICAL FROM THE GROUP CONSISTING OF ARALKYL RADICALS AND LOWER ALKPHATIC HYDROXY HYDROCARBON RADICALS. 